Adaptive uplink/downlink timeslot assignment in a hybrid wireless time division multiple access/code division multiple access communication system

ABSTRACT

A particular cell of a hybrid time division multiple access/code division multiple access communication system has a base station and a plurality of user requirements. Timeslots having unacceptable interference for the uplink are estimated. Timeslots having unacceptable interference for the downlink are estimated. An availability list is produced. The availability list indicates available uplink and downlink timeslots having acceptable interference levels. Uplink and downlink timeslots are assigned using the availability list.

[0001] This application claims priority from Provisional Application No.60/221,009, filed Jul. 27, 2000.

BACKGROUND

[0002] The present invention relates generally to resource allocation inwireless hybrid time division multiple access/code division multipleaccess communication systems. More specifically, the invention relatesto assigning uplink and downlink timeslots in such systems.

[0003]FIG. 1 depicts a wireless communication system. The system has aplurality of base stations 30 ₁-30 ₁₁. Each base station 30 ₁communicates with user equipments (UEs) 32 ₁, 32 ₃, 32 ₄ in itsoperating area or cell. Communications transmitted from the base station30 ₁ to the UE 32 ₁ are referred to as downlink communications andcommunications transmitted from the UE 32 ₁ to the base station 30 ₁ arereferred to as uplink communications.

[0004] In addition to communicating over different frequency spectrums,spread spectrum code division multiple access (CDMA) systems carrymultiple communications over the same spectrum. The multiple signals aredistinguished by their respective chip codes (codes). To moreefficiently use the spread spectrum, some hybrid time division multipleaccess (TDMA)/CDMA systems as illustrated in FIG. 2 use repeating frames34 divided into a number of timeslots 36 _(l)-36 _(n) such as fifteentimeslots. In time division duplex (TDD) systems using CDMA, a timeslotis used either solely for downlink or uplink communications in a cell.In such systems, a communication is sent in selected timeslots 36_(l)-36 _(n) using selected codes. Accordingly, one frame 34 is capableof carrying multiple communications distinguished by both timeslot 36_(l)-36 _(n) and code. The use of a single code in a single timeslotwith a spreading factor of sixteen is referred to as a resource unit.Based on a communication's bandwidth requirements, one or multipleresource units may be assigned to a communication.

[0005] One problem in such systems is cross cell interference asillustrated in FIG. 3. A second cell's base station 30 ₂ sends adownlink communication 40 to a second cell's UE 32 ₂ in a certaintimeslot. In the same timeslot, an uplink communication 38 is sent froma first cell's UE 32 ₁. The uplink communication 38 may be received bythe first cell's base station 30 ₁ at an unacceptable interferencelevel. Although the second cell's base station 30 ₂ is further away thanthe first cell's UE 32 ₁, the higher effective isotopically radiatepower (EIPR) of the second cell's base station 30 ₂ may result inunacceptable interference at the first cell's base station 30 ₁.

[0006] Also shown in FIG. 3 is cross interference between UEs 32 ₁, 32₂. An uplink signal 38 from a first cell's UE 32 ₁ will createunacceptable levels of interference to a downlink communication 40 inthe same timeslot received by the second cell's UE 32 ₂, due to theirclose proximity.

[0007] Accordingly, there exists a need for reducing cross cellinterference.

SUMMARY

[0008] A particular cell of a hybrid time division multiple access/codedivision multiple access communication system has a base station and aplurality of user equipments. Timeslots having unacceptable interferencefor the uplink are estimated. Timeslots having unacceptable interferencefor the downlink are estimated. An availability list is produced. Theavailability list indicates available uplink and downlink timeslotshaving acceptable interference levels. Uplink and downlink timeslots areassigned using the availability list.

BRIEF DESCRIPTION OF THE DRAWING(S)

[0009]FIG. 1 is a wireless spread spectrum CDMA system.

[0010]FIG. 2 illustrates timeslots in repeating frames.

[0011]FIG. 3 illustrates cross cell interference.

[0012]FIG. 4 is an availability list.

[0013]FIG. 5 is a flow chart for generating an availability list usingbase station to base station (BS-BS) and user equipment to userequipment (UE-UE) interference cells.

[0014]FIG. 6 is an example of a cross interference cell list.

[0015]FIG. 7 is a table showing a hypothical timeslot allocation foreach cell.

[0016]FIG. 8 is an availability list for cell 1 constructed using FIGS.6 and 7.

[0017]FIG. 9 is a flow chart for producing an availability list usingonly BS-BS interference cells.

[0018]FIG. 10 is an illustration of a BS-BS cross interference list.

[0019]FIG. 11 is a flow chart for producing an availability list usingonly UE-UE interference cells.

[0020]FIG. 12 is a UE-UE cross interference list.

[0021]FIGS. 13 and 14 are flow charts using base station and userequipment interference measurement to determine timeslot availability.

[0022]FIG. 15 is an illustration of a user equipment specificavailability list.

[0023]FIGS. 16 and 17 are flow charts for using only interferencemeasurements to determine timeslot availability.

[0024]FIGS. 18, 19 and 20 are flow charts for determining timeslotavailability using hybrid approaches.

[0025]FIG. 21 is a flow chart of a timeslot assignment approach.

[0026]FIG. 22 is a flow chart of availability list updating.

[0027]FIG. 23 is the updated table of FIG. 7.

[0028]FIG. 24 is an updated availability list for cell 7 based on FIG.23.

[0029]FIG. 25 is a centralized architecture embodiment.

[0030]FIG. 26 is a decentralized architecture embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0031] Although the following describes timeslot assignment in contextof a TDD/CDMA system, the same timeslot elimination procedures andavailability lists can be applied to a hybrid TDMA/CDMA system whereuplink and downlink communications occur in the same timeslot in a cell.

[0032]FIG. 4 illustrates an availability timeslot list 76. Along thehorizontal axis, each timeslot is listed as S1, S2, . . . , SN. Alongthe vertical axis, each cell, listed here by the subscript of itsassociated base station's reference number, is listed for both theuplink and downlink. Each row indicates the timeslot availability foreither the uplink or the downlink for a cell. Timeslots not availableare indicated with an “X”. Available timeslots are left empty.

[0033] One procedure for generating the availability list is shown inFIG. 5 and is explained in conjunction with FIGS. 6, 7 and 8. Initially,the cross interference between each cell pair is measured. Initially,base station 30 ₁-30 ₁₁ to base station 30 ₁-30 ₁₁ (BS-BS) interferingcells are determined, step 77. BS-BS interfering cells are cells where abase stations 30 ₁-30 ₁₁ transmissions interfere with another basestations 30 ₁-30 ₁₁ reception.

[0034] Each cell determines its BS-BS interfering cells by estimatinginterference from the other cells. One approach estimates the BS-BSinterfering cells using pre-measured link gains between the basestations 30 ₁-30 ₁₁. If the estimated interference exceeds a threshold,the base stations' cells are considered BS-BS interfering cells, step77. Based on the threshold comparison, BS-BS interfering cells aredetermined and stored in a cross interference cell list 84 asillustrated in FIG. 6. The vertical axis of the cross interference celllist 84 has each cell. The horizontal axis has potential crossinterfering cells. A cell that BS-BS interferes with another cell ismarked in the appropriate box by an “I”, step 79. For example, sincecommunications in cell 2 cross interfere with cell 1, the first row,second column box is marked with an “I.” Since a cell does not interferewith itself, these boxes are marked by an “X.”

[0035] Additionally, cells where UEs 32 _(l)-32 _(n) may interfere withother UEs 32 _(l)-32 _(n) are determined, step 78. Due to the relativelylow EIPR of UEs 32 _(l)-32 _(n), the UE-UE interfering cells are inclose geographic proximity, such as being adjacent. One UEs 32 ₁ uplinktransmission can interfere with a neighboring cell's UE reception, asshown in FIG. 3. Since cells with close geographic proximity may haveUEs 32 _(l)-32 _(n) which may interfere with each other, these cells arealso listed as interfering cells. In FIG. 6, the UE-UE interfering cellswhich were not BS-BS interfering cells are marked with an “I*”, step 79.

[0036] Using the cross interference cell list 84, for each cell, thepotential cross interference cells are determined, step 78. For aparticular cell in the vertical axis, each cell in the corresponding rowmarked with an “I” or “I*” is a cross interference cell. For instance,cell 1 is potentially cross interfered by cells 2, 3, 5, 6, 9 and 10.For each cross interference cell, the timeslot allocation is determined.For instance, using the hypothetical timeslot allocation of table 86 ofFIG. 7, cell 2 is allocated downlink timeslots 1 and 2 and uplinktimeslot 9. For each downlink timeslot allocated in a cross interferencecell, a corresponding uplink timeslot is eliminated, step 80. Toillustrate using FIG. 6, 7 and 8, for cell 1, cell 2's allocateddownlink timeslot 1 eliminates timeslot 1 from cell l's available uplinktimeslots as shown by an “X” in cell 1's availability list 88 of FIG. 8.

[0037] For each uplink timeslot allocated in a cross interference cell,a corresponding downlink timeslot is eliminated, step 82. To illustratefor cell 1, cell 2's uplink timeslot 9 eliminates that timeslot fromcell 1's possible downlink timeslots as shown in cell 1's availabilitylist 88. After eliminating the appropriate timeslots due to the crossinterference cells, an availability list 76 for each cell is produced,step 90. As a result, uplink and downlink timeslots used in crossinference cells are made unavailable reducing cross cell interference.

[0038] To relax the assignment conditions, either only the BS-BSinterfering cells or only the UE-UE interfering cells are considered.These approaches may lead to freeing up more resources for each cell.However, the looser criteria may result in unacceptable interferencelevels with respect to some users.

[0039]FIG. 9 is a flow chart for producing an availability list usingonly BS-BS interference cells. The BS-BS interference cells areidentified, step 122. A BS-BS cross interference list 132 is produced,such as in FIG. 10. If a cell uses a timeslot for the uplink, that slotis eliminated for use by BS-BS interfering cells for the downlink, step126. Conversely, if a cell uses a timeslot for the downlink, that slotis eliminated for use by BS-BS interfering cells for the uplink, step128. A list of available timeslots is produced for each cell, step 130.Although this approach more aggressively uses the systems resources,unacceptable downlink interference may be suffered by some users.

[0040]FIG. 11 is a flow chart for producing an availability list usingonly UE-UE interference cells. The UE-UE interference cells areidentified, step 134. A UE-UE cross interference list 142 is produced,such as in FIG. 12. If a cell uses a timeslot for the uplink, that slotis eliminated for use by UE-UE interfering cells for the downlink, step136. Conversely, if a cell uses a timeslot for the uplink, that slot iseliminated for use by UE-UE interfering cells for the downlink, step138. A list of available timeslots for each cell is produced, step 140.This approach may result in unacceptable uplink interference levels forsome users.

[0041] Another approach for determining available timeslots usesinterference measurements of timeslots, such as by interference signalcode power (ISCP). The interference measurements may be taken at thebase stations 30 ₁-30 ₁₁, UEs 32 _(l)-32 _(n) or both.

[0042]FIG. 13 is a flow chart using base station and UE interferencemeasurements to determine available timeslots for each UE 32 _(l)-32_(n). For a particular cell, the interference level in each timeslot ismeasured at the base station 30 ₁, step 144. Each of the cell's UEs 32₁, 32 ₃-32 ₄ also measure interference levels in each timeslot, step146. The timeslot interference measurements by the base stations areused to determine the availability of uplink timeslots. The downlinktimeslot availability is determined on a UE by UE basis (UE specificbasis).

[0043] For the uplink, if the base station's measured interferenceexceeds a threshold in a timeslot, that timeslot is eliminated for theuplink, step 148. For the downlink, each UE 32 ₁, 32 ₃, 32 ₄ eliminatesdownlink timeslots for its use, if that UE's interference measureexceeds a threshold, step 150. An availability list 154 is producedshowing the available uplink timeslots and the available downlinktimeslots for each UE as illustrated in FIG. 15, step 152.

[0044] Although two cells are adjacent, the location of specific UEs 32_(l)-32 _(n) in the cells may be distant. To illustrate using FIG. 1,cell 1 and cell 2 are adjacent. However, a UE 32 ₄ is distant from cell2. Accordingly, if UE 32 ₂ in cell 2 uses a slot for uplink, it willmost likely not interfere with the downlink reception of UE 32 ₄.However, UE 32 ₂ uplink transmissions would likely interfere with UE 32₁ downlink transmissions. As a result, a more aggressive resourceallocation is available using a UE specific availability list 154. Onedrawback is the increased signaling required. Due to UE mobility andother cells' reassignments, the interference measurements must beupdated and signaled to the base station 30 ₁-30 ₁₁ on a frequent basis.

[0045]FIG. 14 is a flow chart using base station and UE interferencemeasurements to determine non-UE specific available timeslots. The basestation 30 ₁ measures the interference in each timeslot, step 144, andso does each UE 32 ₁, 32 ₃, 32 ₄, step 146. For the uplink, if the basestation measured interference exceeds a threshold in a timeslot, thattimeslot is eliminated, step 148. For the downlink, if any of thatcell's UEs measured interference in a timeslot exceeds the threshold,that timeslot is eliminated for the downlink, step 156. Using theeliminated timeslots, an availability list 88 for each cell is produced,such as per FIG. 8. Since the UE measurements are effectively combined,missing UE interference measurements are not critical to resource unitassignment.

[0046]FIGS. 16 and 17 are flow charts using only UE interferencemeasurements to determine available timeslots. In a cell, each UEmeasures the interference in each timeslot, step 160. For the uplink, ifany UE interference measure exceeds the threshold, that timeslot iseliminated for the uplink, step 160. Alternately, to reduce the numberof eliminated uplink timeslots, only the timeslots where most of the UEshave unacceptable interference are eliminated from the uplink, step 160.If only a few UEs report unacceptable interference, it is assumed theseUEs are at the fringe of the cell and are not representative of theoverall cell conditions.

[0047] Using a UE specific assignment approach as in FIG. 16, each UE 32₁, 32 ₃, 32 ₄ has its own set of available downlink timeslots, such asper FIG. 15. For each UE 32 ₁, 32 ₃, 32 ₄, a downlink timeslot iseliminated, if that UE interference measurement on the timeslot exceedsa threshold, step 164. A UE specific availability list 150 is produced,step 166.

[0048] A non-UE specific approach is shown in FIG. 17. If any UE or mostUEs' interference measurement exceeds a threshold in the timeslot, thattimeslot is eliminated for the downlink, step 168. An availability list88, such as in FIG. 8, is produced for the entire cell.

[0049]FIGS. 18, 19 and 20 are timeslot availability determinationapproaches, using hybrid BS-BS interference, UE-UE interference andinterference measurement approaches. FIGS. 18 and 19 use BS-BSinterference cells and UE interference measurements. The BS-BSinterfering cells are determined, step 172. Each UE 32 ₁, 32 ₃, 32 ₄measures the interference in each timeslot, step 174. For the uplink,timeslots are eliminated, if a BS-BS interfering cell uses it for thedownlink, step 176.

[0050] Downlink availability is determined on a UE by UE or a collectivebasis. Using a UE by UE basis per FIG. 18, each UE 32 ₁, 32 ₃, 32 ₄compares each timeslot interference measurement to a threshold. If atimeslot measurement exceeds the threshold, that timeslot is eliminatedfor that UE 32 ₁, 32 ₃, 32 ₄ in the downlink, step 178. A UE specificavailability list 150, such as FIG. 15, is produced, step 180.

[0051] Using a collective basis per FIG. 19, if any UE timeslotinterference measurement exceeds a threshold, that timeslot iseliminated for the downlink for the cell, step 182. An availability list88, such as FIG. 8, is produced, step 184.

[0052]FIG. 20 uses UE-UE interference cells and base stationinterference measurements. A cell's base station 30, measures theinterference levels in each timeslot, step 186. UE-UE interfering cellsare identified, step 188. For the uplink, eliminate uplink timeslots, ifthat timeslot's interference exceeds a threshold, step 190. For thedownlink, a downlink timeslot is eliminated, if a UE-UE interfering celluses it for the uplink, step 192. Based on the eliminated timeslots, anavailability list 88, such as FIG. 8, is produced.

[0053] For sectored cells, the cross interference list and availabilitylists 84 are constructed for each sector within the cells. The crossinterference between all cell's sectors is determined. Although thefollowing discussion focuses on non-sectorized cells, the same approachalso applies to sectorized cells where the assigning is performed on aper sector basis instead of a per cell basis.

[0054] Using the availability list 76, each base station 30 _(l)-30 _(n)is assigned timeslots to support its communications using the procedureof FIG. 21. Initially, a request for an additional allocated timeslot ortimeslots is made, step 92. Referring to that base station'savailability list 76, corresponding available timeslots are assigned. Toillustrate using the availability list 88 of FIG. 8, the base station30, requires both an additional allocated downlink and an uplinktimeslot. The available uplink timeslots are slots 4 and 7-16 and theavailable downlink timeslots are slots 1-3, 5, 6, 8, 10-13 and 16. Oneuplink timeslot and downlink timeslot will be assigned out of thecorresponding available downlink and uplink timeslots. If a UE specificavailability list 150 is used, the downlink assignment is based on theUE 32 _(l)-32 _(n) requiring the downlink resource unit(s).

[0055] Since the base stations 30 _(l)-30 _(n) need to dynamicallyassign and release timeslots due to varying uplink/downlink demand, theinformation in the availability list 76 requires updating. Forapproaches using interference measurements, the updates are performed byupdating the measurements and the lists.

[0056] For BS-BS and UE-UE approaches, this procedure is shown in FIG.22. Initially, the cross interference cells are identified for eachassigned or released timeslot, step 96. For each assigned downlinktimeslot, the corresponding timeslots in the cross interference cellsare eliminated for the uplink, step 98. Conversely, if the uplinktimeslot is assigned, the corresponding timeslots in the crossinterference cells for the downlink are eliminated, step 100. Toillustrate using FIGS. 23 and 24, the base station 30 ₆ associated withcell 6 assigns timeslot 7 for the downlink, “D*”, and timeslot 8 for theuplink, “U*”, as indicated in table 106 of FIG. 23. The crossinterference cells are cells 1, 2, 5 and 7. As shown for cell 7'savailability list 107 of FIG. 24, timeslot 7 is eliminated for theuplink and timeslot 8 is eliminated for the downlink, both marked as“X*”.

[0057] If a downlink timeslot was released, the corresponding timeslotsin the cross interference cells are freed for the uplink unlessunavailable for other reasons, such as being used as a downlink timeslotin another cross interference cell, step 102. For instance, if timeslot6 of cell 6 is released as indicated in table 106 as “D**”, cell 1'suplink timeslot 6 is not made available. Cell 9 is a cross interferencecell to cell 1, which also uses downlink timeslot 6. By contrast, forcell 7, the release of downlink timeslot 6 frees the cell for uplinkcommunications as shown in cell 7's availability list 108 by an “R.” Ifan uplink timeslot was released, the corresponding timeslots in thecross interference cells are freed for the downlink unless unavailablefor other reasons, step 104.

[0058] One approach for using uplink/downlink timeslot assignment isshown in FIG. 25 using a centralized architecture. The radio networkcontroller (RNC) 110 has a resource allocation device 11 to assign orrelease a timeslot based on user demand. If assigning, the resourceallocation device 116 in the RNC 110 assigns an appropriate timeslotusing availability list 76, stored in its memory 117, per the procedureof FIG. 21. The selected timeslots and channel codes are communicated tothe base station 30 _(l)-30 _(N) and UEs 32 _(l)-32 _(N), via the node-Btimeslot assignment and release device 112 _(l)-112 _(n). If releasing atimeslot, the RNC resource allocation device 116 releases that timeslotand updates the availability list 76. Accordingly, updating of theavailability list 76 is centralized by occurring at the RNC 110.

[0059] Another approach for uplink/downlink timeslot assignment is shownin FIG. 36 using a decentralized architecture. Each node-B 122 _(l)-122_(N) has its own timeslot controller 120 _(l)-120 _(n). When a timeslotassignment and release device 112 _(l)-112 _(n) requests timeslots for acommunication, the node-B's timeslot controller 120 _(l)-120 _(n)selects an appropriate timeslot from its availability list 76, as storedin its memory 121 ₁. The stored availability list 76 to reduce its sizemay only contain the available timeslots for that node-B's cell(s).Conversely, the stored availability list 76 may contain the availabilityfor all the RNC's cells. The decentralized approach allows for fasterupdates.

[0060] The selected timeslot is assigned to the communication by thetimeslot assignment and release device 112 _(l)-112 _(n). To update thelists 76, that node-B 122 _(l)-122 _(n) updates its list 76. Theassigned and released timeslots are also sent to the RNC 110. The RNC110 directs the appropriate timeslot update information to the othercells. The timeslot information either contains an updated availabilitylist 76 or merely the changes to the list 76. If only the changes aresent, each cell's controller 120 _(l)-120 _(n) updates its ownavailability list 76 with that information. The type of timeslotinformation sent is based on the processing and signaling requirementsof the system.

[0061] Assigning uplink/downlink timeslots is adaptable to systemssupporting differing signaling rates. For systems supporting only slownetwork signaling, the allocated timeslot information is updated on adaily basis using a statistical analysis of the uplink/downlink demand.Since communication traffic varies during the day, a faster update rateperforms better and is preferred. For medium speed network signaling,the updating is performed periodically ranging from a fraction of anhour to several hours. Medium speed network signaling also usesstatistical analysis but over a shorter time period. For fast networksignaling, the allocated timeslots are updated on a per call basis orframe basis. Once a timeslot is assigned or released, the appropriatelists are updated. The fast network signaling allocates timeslots on anas needed basis. As a result, it more efficiently uses the system'sresources.

What is claimed is:
 1. A method for assigning timeslots for a particularcell of a hybrid time division multiple access/code division multipleaccess communication system, the system having a plurality of cellscomprising the particular cell and other cells, the method comprising:determining potentially interfering ones of the other cells whichpotentially interfere with the particular cell; for each timeslot,eliminate that timeslot for uplink communication, if first ones of thepotentially interfering ones uses that timeslot for downlinkcommunications; for each timeslot, eliminate that timeslot for downlinkcommunication, if second ones of the potentially interfering ones usesthat timeslot for uplink communications; assigning a timeslot to anuplink communication of the particular cell using non-uplink eliminationtimeslots; and assigning a timeslot to a downlink communication of theparticular cell using non-downlink eliminated timeslots.
 2. The methodof claim 1 wherein the first ones are base station to base stationinterfering cells to the particular cell.
 3. The method of claim 2wherein the base station to base station interfering cells aredetermined by using link gains between base stations.
 4. The method ofclaim 1 wherein the first ones and the second ones are base station tobase station interfering cells to the particular cell.
 5. The method ofclaim 1 wherein the second ones are user equipment to user equipmentinterfering cells to the particular cell.
 6. The method of claim 5wherein the user equipment to user equipment interfering cells aregeographically nearby cells to the particular cell.
 7. The method ofclaim 6 wherein the geographically nearby cells are adjacent cells. 8.The method of claim 1 wherein the first and second ones are userequipment to user equipment interfering cells to the particular cell. 9.The method of claim 1 wherein the hybrid time division multipleaccess/code division multiple access communication system is a timedivision duplex communication system using code division multipleaccess.
 10. A hybrid time division multiple access/code divisionmultiple access communication system comprising: a plurality of cellsincluding a particular cell and other cells; the particular cellcomprising: means for determining potentially interfering ones of theother cells which potentially interfere with the particular cell; meansfor each timeslot, for eliminating that timeslot for uplinkcommunication, if first ones of the potentially interfering ones usesthat timeslot for downlink communications; means for assigning atimeslot to an uplink communication using non-uplink eliminatedtimeslots; and means for assigning a timeslot to a downlinkcommunication using non-downlink eliminated timeslots.
 11. The system ofclaim 10 wherein the first ones are base station to base stationinterfering cells to the particular cell.
 12. The system of claim 11wherein the base station to base station interfering cells aredetermined by using link gains between base stations.
 13. The system ofclaim 10 wherein the first ones and the second ones are base station tobase station interfering cells to the particular cell.
 14. The system ofclaim 10 wherein the second ones are user equipment to user equipmentinterfering cells to the particular cell.
 15. The system of claim 14wherein the user equipment to user equipment interfering cells aregeographically nearby cells to the particular cell.
 16. The system ofclaim 15 wherein the geographically nearby cells are adjacent cells. 17.The system of claim 10 wherein the first and second ones are userequipment to user equipment interfering cells to the particular cell.18. The system of claim 10 wherein the hybrid time division multipleaccess/code division multiple access communication system is a timedivision duplex communication system using code division multipleaccess.
 19. A hybrid time division multiple access/code divisionmultiple access communication system comprising: a plurality of cellsincluding a particular cell and other cells; a radio network controllerassociated with the particular cell comprising: a resource allocationdevice for determining potentially interfering ones of the other cellswhich potentially interfere with the particular cell; for each timeslot,eliminating that timeslot for uplink communication, if first ones of thepotentially interfering ones uses that timeslot for downlinkcommunications; and for each timeslot, for eliminating that timeslot fordownlink communication, if second ones of the potentially interferingones uses that timeslot for uplink communication; and a node-Bassociated with the particular cell comprising an assignment and releasedevice for assigning an uplink communication using non-uplink eliminatedtimeslots and for assigning a downlink communication, using non-downlinkeliminated timeslots.
 20. The system of claim 19 wherein the first onesare base station to base station interfering cells to the particularcell.
 21. The system of claim 20 wherein the base station to basestation interfering cells are determined by using link gains betweenbase stations.
 22. The system of claim 19 wherein the first ones and thesecond ones are base station to base station interfering cells to theparticular cell.
 23. The system of claim 19 wherein the second ones areuser equipment to user equipment interfering cells to the particularcell.
 24. The system of claim 23 wherein the user equipment to userequipment interfering cells are geographically nearby cells to theparticular cell.
 25. The system of claim 24 wherein the geographicallynearby cells are adjacent cells.
 26. The system of claim 19 wherein thefirst and second ones are user equipment to user equipment interferingcells to the particular cell.
 27. The system of claim 19 wherein thehybrid time division multiple access/code division multiple accesscommunication system is a time division duplex communication systemusing code division multiple access.
 28. A method for assigningtimeslots in a particular cell of a hybrid time division multipleaccess/code division multiple access communication system, theparticular cell comprising a base station and a plurality of userequipments, the method comprising: (a) estimating timeslots having anunacceptable interference for uplink communications with respect to thebase station; (b) estimating timeslots having an unacceptableinterference for downlink communication with respect to the userequipments; (c) producing an availability list indicating availableuplink and downlink timeslots having acceptable interference levels; and(d) assigning uplink and downlink timeslots using the availability list.29. The method of claim 28 wherein the step (a) comprises measuring aninterference level in each timeslot at the base station and comparingthe measured level to a threshold to estimate unacceptable interference.30. The method of claim 28 wherein the step (a) comprises determiningbase station to base station (BS-BS) cross interfering cells withrespect to the particular cell and estimating the unacceptableinterference if any of the determined BS-BS interfering cells uses atimeslot for the downlink.
 31. The method of claim 28 wherein the step(b) comprises measuring an interference level in each timeslot by eachuser equipment and comparing the measured levels to a threshold toestimate unacceptable interference.
 32. The method of claim 28 whereinthe step (b) comprises determining user equipment to user equipment(UE-UE) cross interfering cells with respect to the particular cell andestimating the unacceptable interference in a particular timeslot if anyof the determined UE-UE interfering cells uses the particular timeslotfor the uplink.
 33. A hybrid time division multiple access/code divisionmultiple access communication system comprising: a particular cellcomprising: a base station and a plurality of user equipments; firstmeans for estimating timeslots having an unacceptable interference withrespect to the base station; second means for estimating timeslotshaving an unacceptable interference for downlink communication withrespect to the user equipments; third means for producing anavailability list indicating available uplink and downlink timeslotshaving acceptable interference levels; and fourth means for assigninguplink and downlink timeslots using the availability list.
 34. Thesystem of claim 33 wherein the first means measures an interferencelevel in each timeslot at the base station and compares the measuredlevel to a threshold to estimate unacceptable interference.
 35. Thesystem of claim 33 wherein the first means determines base station tobase station (BS-BS) cross interfering cells with respect to theparticular cell and estimates the unacceptable interference if any ofthe determined BS-BS interfering cells uses a timeslot for the downlink.36. The system of claim 33 wherein the second means measures aninterference level in each timeslot by each user equipment and comparingthe measured levels to a threshold to estimate unacceptableinterference.
 37. The system of claim 33 wherein the second meansdetermines user equipment to user equipment (UE-UE) cross interferingcells with respect to the particular cell and estimating the acceptableinterference in a particular timeslot if any of the determined UE-UEinterfering cells uses the particular timeslot for the uplink.
 38. Ahybrid time division multiple access/code division multiple accesscommunication system comprising: a particular cell comprising: a basestation and a plurality of user equipments; a node-B comprising atimeslot assignment and release device for assigning uplink and downlinktimeslots using an availability list; and a radio network controllercomprising a resource allocation device for estimating timeslots havingan unacceptable interference with respect to the base station, forestimating timeslots having an unacceptable interference for downlinkcommunications with respect to the user equipments, and for producingthe availability list indicating available uplink and downlink timeslotshaving acceptable interference levels.
 39. The system of claim 38further comprising a memory associated with the resource allocationdevice for storing the availability list.
 40. The system of claim 38wherein the node-B further comprises a timeslot controller for updatingat least a portion of the availability list and a memory for storing theat least a portion.
 41. The system of claim 40 wherein the at least aportion is an entire version of the availability list.
 42. The system ofclaim 40 wherein in the at least a portion is only information from theavailability list pertaining to the particular cell.